This invention relates generally to the construction of retaining walls used in landscaping applications. Such walls are used to provide lateral support between differing ground levels where the change in one elevation to the other occurs over a relatively short distance, thereby reducing the possibility of erosion and landslides. Retaining walls can be both functional and decorative and range from small gardening applications to large-scale construction. They are constructed of a variety of materials and shapes. Some have been constructed of wood timbers, others of rock in a natural form (such as limestone). Still others have been constructed of manufactured aggregate or concrete blocks. The present invention relates to a manufactured block.
Constructing a fit and true retaining wall can be an arduous endeavor. In addition to laying a level first course on ground that is usually located at the foot or in the side of a steep embankment, the builder must ensure that each subsequent course is level. An error made in a lower course is usually exaggerated as higher courses are stacked above it. As a wall made of blocks necessarily develops somewhat of a grid-like appearance, interruptions or undulations in the lines of the wall become readily apparent to the human eye.
One particular problem the prior art has failed to overcome is developing a retaining wall block shaped to avoid these undulations and interruptions which are caused by blocks being stacked on dirt or debris found on the upper surface of the lower course of blocks. Dirt presents itself as a result of the fill material used to fill the gap between the rear of the wall and the earth it is being built to retain. This fill material usually consists of small, coarse rocks. They serve as a barrier between the earth and the wall and prevent wet earth from seeping through the bricks of the wall during inclement weather. Present wall building methods include laying a course of blocks, filling the space behind the course with fill material, packing the fill material, and carefully sweeping the dirt off each completed course prior to the addition of the next course. This final, sweeping step is time consuming but necessary to ensure the next course of blocks lies flat on the lower course.
Some larger blocks incorporate continuous cavities that extend from their bottom surface to their top surfaces. These cavities are intended to reduce the amount of material required to form the block, thereby reducing its cost and weight, and also allow an area to be filled with fill material once a course is finished. At first blush it would appear that, because the presence of cavities reduces the surface area of the top and bottom of the block, they would also serve to decrease the area for interference by small stones and debris between courses. However, because the cavities are filled with fill material, the fill material spills over the upper surfaces and exacerbates, rather than alleviates, the problem. Furthermore, smaller blocks cannot incorporate cavity portions without jeopardizing their structural integrity.
The inability of smaller blocks to accommodate cavity portions creates further problems. Making a solid block out of concrete results in a dense rock that is heavy for its relatively small size. Working with these rocks can become cumbersome. The absence of cavities or interruption in the sidewalls makes these blocks difficult to lift. They have few areas that lend themselves to easy gripping and lifting. This becomes an important consideration in light of the number of blocks that must be lifted and set in place during the construction of even a relatively small retaining wall.
It would be desirable to develop a retaining wall block shaped to accept a certain amount of dirt and debris from course to course without adversely affecting the overall structure and aesthetics of the resulting wall. It would also be desirable to devise a small retaining wall block which is has a reduced unit weight due to the absence of block material in an area that will not adversely affect the strength of the block, nor its appearance. Finally, it would be desirable to provide a small retaining wall block that is relatively easy to grasp and pick up off a stack of similar blocks.